1. Field of the Invention
The invention pertains to a refractory composite slab comprising three layers that consist essentially of inorganic expanded materials of various grain sizes, such as expanded vermiculite, which are glued with bonding agents and subsequently compressed, where at least two layers of such expanded materials are provided, between which a flat reenforcement layer is located, as well as its use.
2. Description of Related Art
Three-layer slab composites of the above-mentioned type have been known to the art previously, for instance, from CH-A-590 798. These, however, are not fire-resistant because they contain a core layer of magnesite-cemented wood wool.
A process for the production of non-combustible fire-resistant slab composites that are composed of three layers comprised of expanded materials, such as vermiculite and perlite, has already been known to the art from EP-A1-43144. In this slab composite, each material forms a slab layer of its own. In order to manufacture the individual slab layers, a granulate composed of the above-mentioned inorganic expanded materials is mixed with a binder material, which may be based, for instance, on thermosetting resins in a combination with phosphates. Having been treated in this manner, the granulate is then compressed into slabs.
Due to the exclusive use of inorganic materials, the finished fire-resistant slab composites have a high weight, as well as relatively high stiffness values. Consequently, their further processing, for instance in the context of the usual molding processes, ranges from difficult to impossible.
Therefore, in accordance with DE-A-26 00 024, the amount of inorganic expanded materials was reduced by providing layers made of fibrous media that were bonded with a binder. It is true that, as a result, the weight of the slab is reduced; however, international fire protection standards can no longer be met.